JP2020502473A - Premix fuel nozzle and combustor for gas turbine - Google Patents

Abstract

A nozzle tip (24) for a premixed fuel nozzle (12, 22) is provided. The nozzle tip (24) includes an outer body (26) having an outer body outer surface (36) facing the downstream end of the burner tube (25). The outer body outer surface (36) has a cross-sectional area smaller than the cross-sectional area of the burner tube (25) and radially outwardly from the outer body (26) toward the inner wall (27) of the burner tube (25). A divergent segment having one or more segments (40), each segment (40) disposed in a direction toward the burner tube (25) with a proximal end (44) disposed adjacent the outer body outer surface (36). A distal end (46). Each segment (40) comprises a segment downstream surface (48) inclined toward the downstream end of the burner tube (25) with respect to the longitudinal axis (B) of the burner tube (25). When the gas turbine is operating, an axial flow field of the air and fuel mixture is passed through the burner tube (25) around the nozzle tip (24) to provide strong flame holding and flame propagation. And two or more recirculation zones of varying radial length are created on the nozzle tip (24) by the segments (40).

Description

  The present invention relates to a combustor for a gas turbine. More specifically, the present invention relates to an improved fuel nozzle for a combustor for a gas turbine.

  A typical gas turbine produces work using a combustor to generate high temperature, high pressure combustion gases, as commonly used in power generation. Such a gas turbine typically includes an inlet, a compressor, a combustion, a turbine, and an exhaust. More specifically, the compressor section supplies the compressed working fluid to the combustion section. The compressed working fluid and fuel are mixed in the combustion section and burned to generate high-temperature, high-pressure combustion gas. The combustion gases flow to the turbine section where they expand to produce work. The expanded gas is discharged to the exhaust part.

  The combustion section includes one or more combustors, each of which includes a combustion casing, an end cover, a cap, a fuel nozzle (including a central premix nozzle and a plurality of outer premix nozzles surrounding the central premix nozzle), a liner. , A flow sleeve and a transition piece. The central premix nozzle and the outer premix nozzle take fuel directly from the outer connections of the engine or fuel manifold (end cover) and deliver it to the combustor.

  Nozzle requirements include supplying the various fluids supplied by the end covers to their desired injection ports, providing flow and fuel distribution for the combustor to function properly, and the required maintenance windows. Meanwhile, maintaining the flame adjacent the nozzle without damaging the combustor, and properly sealing the passage to provide a leak-free seal.

  With respect to flame holding nozzles, most combustors have a position on the nozzle that "holds" the flame. Holding the flame requires an area of the combustor where the flow is generally slow and the residence time is relatively long. This area is further replaced by a mainstream area that exchanges and lowers the partially burned combustion products with the mainstream area, which itself provides more fuel and air for combustion to keep the area hot. Recharged.

  Relatively little heat release occurs in the flame holding zone. For example, 6% of the total combustion chamber heat release may occur in the flame holding zone. However, these zones are very important because they define the stability and shape of the flame and thus the success of the combustor.

  Previous flameholder concepts have generally been either blunt bodies or swivel stabilization. Flame holding of a blunt body is where a portion of the combustor forms a low velocity zone downstream of it, where the axial flow velocity is low enough to allow the flame to stay in it. For example, as found in US Pat. No. 7,003,961 (Kendrick et al.), Most of such devices generate vortices trapped therein or partially trapped therein. . The stabilization of swirl stabilization is achieved by a swirler swirling the flow, which then spontaneously burns and recirculates to its center, as found, for example, in US Pat. No. 6,438,961 (Tuthill et al.) A place to form. The flame can be stably present in the generated toroidal vortex and ignite the inner surface of the flow through the burner tube. Depending on the geometry / expansion ratio, there may be vortices outside the flow and may form a flame stabilizer. Some systems use a combination of blunt bodies and flame stabilization for pivot stabilization.

US Patent No. 7,003,961 U.S. Pat. No. 6,438,961

  In most designs for the nozzle, it is advantageous for the flame to be fixed at its downstream tip. The tips are often not large in that they occupy the flow area. Thus, the larger the chip size, the larger the burner tube needs to be to maintain the same flow area. Alternatively, if burner tubes of the same size are used, the flow rate needs to be increased. This results in increased losses. It is advantageous to have the largest possible recirculation zone, and it is typically more stable. The recirculation zone provides hot products from the upstream reaction zone along the nozzle centerline for mixing with the fresh fuel-air mixture supplied by the nozzle. One way to increase the size of the recirculation zone is to swirl the flow. Blades in the premixing zone rotate the flow. This stream passes through the annular pipe to the end of the nozzle or slightly beyond (if the tip is concave). When the swirling flow is no longer confined in free space, the flow expands because there is no constraining force applied by the walls of the annular tube. This expanded flow shears the air inside. Because it is pushing the outside air downstream, the air must come upstream on the centerline to replace the air being displaced. Thus, the flow shearing on the outside also rotates in the direction of the swirl, so that this flow forms a toroidal vortex.

  In premix nozzle designs, in many configurations, most of the air passes through the upstream surface of the liner to be mixed with fuel before entering the liner and burning.

  Turning the flow has multiple consequences. Swirl the flow at 45 degrees versus 25 degrees, for example, results in a higher pressure drop, which can exhaust 390 KW of energy in a 70 MW gas turbine, for example. The energy is dissipated as heat, some of which is recovered as it expands throughout the cycle, leading to a reduction in overall power and efficiency. Obviously, not swirling the flow at all would provide even greater benefits.

  One way to reduce pressure loss is to reduce the speed of the flow in the burner tube, since the loss is proportional to the square of the speed. The presence of a larger burner tube results in less open cap space available for expansion. It also places the flow streams close to each other, which increases the shear rate between the streams leaving the premixer.

  The use of swirling flow makes it very difficult or impossible to design a nozzle without circular symmetry. In addition, it is very difficult to design the shape of a flame by changing its properties in the circumferential direction, as the rotational properties of the flow constantly change its relationship to physical features such as liners and adjacent nozzles. Have difficulty. One area where turning can help is mixing. Longer spiral channels resulting from swirling flow result in longer distances for mixing to occur.

  Outer nozzles have inherent advantages in swirl-based systems. By design / concept, the nozzle has circular symmetry. Although the shape and characteristics of the flame can vary, typically only radial characteristics such as fuel profile or swirl can be varied.

In the fuel nozzle, air and fuel are premixed before combustion. By premixing the fuel and air, the air is effectively a diluent because more air is mixed with the fuel than is needed to burn all the fuel, and as the fuel burns, Heat both the combustion products and excess air simultaneously. The production of the pollutant NO _x (nitrous oxide) is strongly related to temperature. Therefore, minimizing the flame temperature minimizes NO _x production.

  It would be desirable to create a nozzle structure that utilizes axial flow rather than swirl to produce a strong local flame retention (flame holding) and flame propagation that allows for the design of downstream flame sheet shapes. . This can have a linear flow, as any part of the nozzle tip can be unique. "Axial flow" for the purposes of the present invention is intended to mean a flow field having a nominally zero net vortex. As defined, "axial flow" may have a secondary motion. In this case, it may have a flow characteristic with a radial velocity and a circumferential velocity, but the net swirl / radial velocity is essentially zero.

  All references cited herein are hereby incorporated by reference in their entirety.

  A premixed fuel nozzle for a gas turbine is provided that includes a nozzle tip disposed within a burner tube. The burner tube has an inner wall, an open interior volume having a length extending between an upstream end and a downstream end of the burner tube, a longitudinal axis, and a cross-sectional area perpendicular to the longitudinal axis. The nozzle tip includes an outer body having an outer body outer surface facing the downstream end of the burner tube. The outer body outer surface has a cross-sectional area smaller than the cross-sectional area of the burner tube. The nozzle tip further includes one or more segments radiating radially outward from the outer body toward the inner wall of the burner tube, each segment having a proximal end disposed adjacent the outer body outer surface. , A distal end disposed in a direction toward the burner tube. Each segment has a segment downstream surface that is inclined toward the downstream end of the burner tube with respect to the longitudinal axis of the burner tube. When the gas turbine is in operation, an axial flow field of the air and fuel mixture flows around the nozzle tip through the burner tube to provide strong flame holding and flame propagation, and a radial Two or more recirculation zones of different lengths are created on the nozzle tip by the segments.

  At least one distal end of the segment may extend partially or completely to the inner wall of the burner tube. The outer body may surround the inner plenum, the inner plenum adapted to receive cooling air. Here, the outer body has an open end and a closed end, and the closed end has an inner surface adjacent the inner plenum. The closed end may have a plurality of cooling holes extending between the inner surface and the outer body outer surface.

  Each segment has an open proximal end and a closed distal end, and the open proximal end may have an internal conduit in fluid communication with the inner plenum, wherein air passes from the inner plenum to the inner conduit. It is supposed to. Each segment may have a plurality of segment boreholes between the inner conduit and the segment downstream surface, and a borehole is formed between the inner conduit and the segment downstream surface to allow air to pass through each segment from the inner conduit. Providing fluid communication between the surfaces. The segment downstream surface of each segment may be flat. The angle of the segment downstream surface with respect to the longitudinal axis B of the burner tube 25 may be, for example, in a range of 105 to 165 degrees (for example, about 135 degrees). The distal end of at least one segment that extends completely to the inner wall of the burner tube is closed and may include a purge groove. Each of the segments may be circumferentially equally spaced around the outer body. The circumferential cross-sectional area at the proximal end of each segment may be greater than the circumferential cross-sectional area at the distal end of each segment. Each segment may have a U-shaped cross-section, the cross-section being parallel to the longitudinal axis of the burner tube. Each segment may have an upstream surface, and the upstream surface may be smoothly curved toward the segment downstream surface. Each segment may have an upstream surface, and the upstream surface of each segment may be inclined toward the downstream end of the burner tube with respect to the longitudinal axis of the burner tube.

  A combustor for a gas turbine including a reaction zone and one or more premixed fuel nozzles is also provided. The premixed fuel nozzle is for injecting a mixture of fuel and air into the reaction zone. The at least one premixed fuel nozzle may include a fuel air premixer and a nozzle tip located within the burner tube. The burner tube has an inner wall, an open interior volume having a length extending between an upstream end and a downstream end of the burner tube, a longitudinal axis, and a cross-sectional area perpendicular to the longitudinal axis. The nozzle tip is as described above. When the gas turbine is in operation, an axial flow field of the air and fuel mixture flows around the nozzle tip through the burner tube to provide strong flame holding and flame propagation, and a radial Two or more recirculation zones of different lengths are created on the nozzle tip by the segments. The at least one premixed fuel nozzle may be a single central premixed fuel nozzle, and the combustor includes at least one outer premixed fuel nozzle of a different type. One or more premixed fuel nozzles may include a single central premixed fuel nozzle and at least one outer premixed fuel nozzle.

  The present invention is described in conjunction with the following drawings, wherein like reference numbers indicate like elements.

1 is a simplified cross-sectional elevation view of a gas turbine combustor having a premixed fuel nozzle according to an exemplary embodiment of the present invention. FIG. 2 is a front isometric view of the cap front plate, premix nozzle and burner tube of the combustor of FIG. 1. FIG. 3 is a rear isometric view of the cap front plate and burner tube of FIG. 2 and is shown without an outer premixed fuel nozzle for clarity. FIG. 3 is a front elevation view of the cap front plate and the burner tube of FIG. 2. FIG. 2 is a front elevation view of a nozzle tip for the premixed fuel nozzle of FIG. 1. FIG. 6 is a rear view of the nozzle tip of FIG. 5. FIG. 6 is a front isometric view of the nozzle tip of FIG. 5. FIG. 8 is an isometric cross-sectional view of the cap front plate, premix nozzle, and burner tube of FIG. 2 substantially along line 8-8 of FIG. FIG. 9 is an isometric cross-sectional view of the central nozzle assembly of FIG. 6 substantially along line 9-9 of FIG. FIG. 2 is a front isometric view of an alternative nozzle tip for the premixed fuel nozzle of FIG. 1. FIG. 11 is a front elevation view of a nozzle tip for the premixed fuel nozzle of FIG. 10. It is a rear view of the nozzle front-end | tip part of FIG. FIG. 13 is an isometric cross-sectional view of the central nozzle assembly of FIG. 6, substantially taken along line 13-13 of FIG. 10. Figure 4 is a simplified partial simulated flow field through the burner tube of the present invention and around the nozzle tip, where the flow field is shown around a segment of the nozzle tip. In contrast to the present invention, it is a simplified partial simulated flow field representing the periphery of a nozzle tip having a segment downstream surface that passes through the burner tube and is not inclined with respect to the longitudinal axis of the burner tube. . Figure 3 is a simplified partial simulated flow field through the burner tube of the present invention and around the nozzle tip, the flow field being shown between the segments. In contrast to the present invention, a simplified partial simulated flow field representing the periphery of a nozzle tip having a segment downstream surface that passes through the burner tube and is not inclined with respect to the longitudinal axis of the burner tube. , The flow fields are shown between the segments.

  The present invention will be described in more detail with reference to the following embodiments, but it should be understood that the present invention should not be deemed to be limited thereto.

  Referring to the drawings, wherein like reference numbers refer to like elements in the several figures, FIG. 1 has a premix nozzle 12, 22 according to a first exemplary embodiment of the present invention. 1 shows a combustor 10. The main components of the combustor 10 include a combustion casing 14, an end cover 16, a cap 18, a reaction zone 20, a central premixed fuel nozzle 12, and a plurality of outer premixed fuel nozzles 22. The nozzles 12, 22 are for injecting a mixture 21 of air and fuel into the reaction zone 20.

  As best shown in FIGS. 2-9, the premixed fuel nozzles 12, 22 generally include a fuel air premixer 23, a nozzle tip 24, and a burner tube 25. It should be noted that the invention relating to nozzle tip 24 may be used fully with some or all of the central premixed fuel nozzle 12 and the outer premixed fuel nozzle. For clarity, the present invention is described herein generally with reference to a central premix nozzle only, but the nozzle tip 24 of the present invention may be used with any of the nozzles 12,22.

  The nozzle tip 24 includes an outer body 26 surrounding an optional inner plenum 28. The burner tube 25 has an inner wall 27, an open inner volume 29, and a length 31 extending between an upstream end 33 and a downstream end 35 of the burner tube 25 (see FIG. 8). The burner tube 25 has a longitudinal axis B and a cross-sectional area 39 perpendicular to the burner tube 25 (shown in FIG. 4 as a cross-hatched area).

  The outer body 26 of the nozzle tip 24 has an open end 30, a closed end 32, and an outer body outer surface 36 on the closed end 32 facing the downstream end 35 of the burner tube 25. The outer body outer surface 36 faces the downstream end 35 of the burner tube 25 and has a cross-sectional area 37 smaller than the cross-sectional area 39 of the burner tube 25 (compare the hatched and cross-hatched portions in FIG. 4). . Outer body outer surface 36 may be planar.

  Optional inner plenum 28 is adapted to receive cooling air. The closed end 32 of the nozzle tip 24 has an inner surface 34 adjacent the inner plenum 28. The closed end 32 has a plurality of bore holes 38 extending between an inner surface 34 and an outer body outer surface 36. As is known in the art, these bore holes 38 can be arranged at an angle to the longitudinal axis B of the burner tube 25.

  As shown in FIGS. 5 to 9, at least one segment 40 extends radially outward from the outer body 26 toward the inner wall 27 of the burner tube 25, for example, at equal circumferential intervals. Each segment 40 can be the same or different lengths and can extend completely to the inner wall 27 of the burner tube or partially extend to the inner wall 27 of the burner tube. An example of a burner tip 24 'having segments of different lengths at irregular angles 40' is shown in FIGS. Burner tip 24 'is shown without any boreholes (described below).

  For the central premix nozzle 12, the simplest use is to have as many segments 40 as the number of outer premix nozzles 22. One replacement method is to have the segment 40 line up with the outer premix nozzle 22 and carry the flame from the central premix nozzle 12 to the outer premix fuel nozzle 22.

  As best seen in FIG. 9, each segment 40 can have an internal conduit 42 having an open proximal end 44 (see FIG. 8) in fluid communication with the inner plenum 28, where air is removed from the inner plenum 28. It is configured to pass into the internal conduit 42. Each segment 40 also includes a closed distal end 46, a segment downstream surface 48 (eg, a plane) disposed adjacent the outer body outer surface 36 of the outer body 26, and optionally, an inner conduit 42 and a segment downstream surface 48. Have a plurality of segment boreholes 50 between them. Boreholes 50 provide fluid communication between internal conduit 42 and segment downstream surface 48 to allow air to pass from internal conduit 42 through each segment 40. The segment downstream surface 48 of each segment 40 is inclined with respect to the longitudinal axis B of the burner tube 25, for example, from 105 ° to 165 °. See, for example, FIG. 9, angle C.

  The closed distal end 46 of each segment 40 can include a purge groove 54 that ensures that there is always a flow of the air and fuel mixture past the nozzle tip 24. If the segment 40 is about the same height as the burner tube 25 and extends to the inner wall 27 of the burner tube (eg, as shown in FIGS. 4 and 8), the purge groove 54 may be in contact with the two portions or Ensures that the area of the distal end 46 of the segment 40 is continuously flushed, even when in substantial contact. Such purge grooves 54 are not required for shorter length segments 40 ', as shown in FIGS.

  Segment 40 may be shaped as shown in various figures (see FIGS. 2 and 4-12). However, it is the intent of the present invention to include virtually any elongated configuration of segments that function properly to achieve the desired result as described herein. In general, the upstream portions of the various segments 40 have a suitable aerodynamic shape to ensure that there is substantially no separation zone upstream of the trailing edge (ie, the edge of the segment downstream surface 48 of the segment 40). Should have. However, it is substantially less important that the various segments have such a clean aerodynamic trailing edge. The various segments 40 on the nozzle tip 24 may have the same physical shape, but, alternatively, a strong flame holding and a strong flame as long as the desired results described herein are achieved. One or more segments 40 on nozzle tip 24, including flame propagation, may have quite different shapes.

  With this configuration, the nozzle tip 24 forms two or more recirculation zones of different radial extent and forms an irregular toroidal recirculation zone 52 of the fuel and air mixture to provide strong retention. Provides flame and flame spread. Note that a typical swirl nozzle has a single toroidal vortex that is the object to be rotated. In the present invention, the recirculation zone is composed of two or more zones of different radial extent and is an irregular toroid, ie not a rotating object graphic. The present invention creates vortices of different sizes that can be adjusted to create different flame shapes with different properties.

  The present invention substantially reduces the air velocity in order to create a low velocity flow area on the downstream side where the axial velocity is lower than the flame velocity and which is rotated by the flow passing between the burner tube and the distal end 46 of the segment 40. And a segment 40 for piercing the flow of the fuel and fuel mixture.

  The segment 40 of the nozzle tip 24 is such that the central premix nozzle 12, which is always active when aligned with the outer premix nozzle 22, shares a flame and turns on or off during the gas turbine loading process. An apparatus for igniting the mixing nozzle 22 is provided. Here, the flow moves from outside the center nozzle tip to the outside nozzle.

  The problem solved by the present invention resides in the creation of a nozzle structure that uses a linear flow instead of a swirl flow. The present invention creates a recirculation zone on the nozzle tip with toroidal flow features of two or more sizes. This produces strong local flame holding and flame propagation, but the simplicity of the flow field allows for an explicit design of the downstream flame sheet geometry, ie its properties (within the physical limits of the design) Things.

  It is an object of the present invention to form a recirculation region having a different radial direction downstream of the nozzle tip. In the swirl design, the tip has circular symmetry and has a rotating shape for flow swirl. It is not necessary for designs using linear flow, as in the present invention. Any part of the tip can be unique.

An advantage of the present invention is that it provides some of the features of a larger nozzle to a smaller nozzle. For example, the present invention: • Increases and strengthens the mass flow recirculating downstream of the nozzle.
• Bring the flame to the outer radius of the burner tube to illuminate the flow over the cap.
The ability to impart different properties to the nozzle tip, which can affect the shape of the flame without altering other parts,
o The size of each segment (height / width / shape / slope) and its relationship to the other segments is arbitrary, giving great flexibility.
-The presence of multiple semi-independent flame stabilizers allows various parts to traverse the light if they are beginning to fade. This results in exceptional lean blowout (LBO), the lowest stoichiometry at which the nozzle can still reliably hold the flame.

  The present invention provides the ability to directly design the shape / geometric properties of the flame. In the past, nozzle characteristics were altered to cause changes in the characteristics of the flame, but the exact nature of the change was not well known. Even with the relatively simple geometry of the combustor, the complex interactions of the swirl flow may make a true design virtually impossible. The effect of turning means that the timing of any property changes with axial distance, so that the change may be advantageous in some respects and disadvantageous in another.

  It should be noted that the present invention requires that each segment 40 have a segment downstream surface 48 that is angled with respect to the burner tube longitudinal axis B toward the downstream end of the burner tube 25. Due to the fact that the downstream surface 48 is inclined, when the gas turbine is operating, the axial flow field of the air and fuel mixture flows around the nozzle tip through the burner tube and the radial direction Two or more different recirculation zones flow. The segments cause the nozzle tip to spread, and a strong flame holding property and flame propagation property are obtained.

  This result does not occur if the segment is present, but the downstream surface of the segment is not inclined toward the downstream end of the burner tube with respect to the longitudinal axis of the burner tube. FIG. 14a shows a partially simplified simulated flow field around the nozzle tip 24 through the burner tube 25 of the present invention wherein the segment 40 has a downstream surface 48 inclined relative to the longitudinal axis B of the burner tube. 15a and a burner according to the invention in which the segment 40b has a downstream surface 48b in which the segment 40b is not inclined with respect to the longitudinal axis B 'of the burner tube 25b (ie perpendicular to the longitudinal axis B' of the burner tube 25b). Compare FIG. 14b and FIG. 15b, which show a simulated flow field around the nozzle tip 24b through the tube 25b. FIG. 14a shows a recirculation area of the same size as the segment height, and FIG. 14b does not.

  An important feature of the segmented nozzle tip 24 of the present invention is its ability to form two or more vortices of different sizes downstream of the segment downstream surface 48. The flow passing between the burner tube 25 of the nozzle tip 24, the segment downstream surface 48, and the outer body 26 shears air downstream of the segment downstream surface 48. This shear movement carries the flow downstream. Thus, the flow of the air-fuel mixture 21 moves on the centerline of the nozzle, replacing the displaced flow. As the very rapid wake begins to pass below the burner tube 25, vortices increase downstream of the nozzle tip 24. Because the nozzle tip 24 and the outer surface of the segment 40 have different radial dimensions, the vortices associated with these structures will be of different sizes as well. Downstream of each segment 40 is a vortex formed one in each region between the segments 40. Thus, the total number of vortex structures is equal to twice the number of segments 40, at least two for a single segment 40.

  This result does not occur with the blunt body system shown in, for example, the flame stabilizer of FIG. 4 of U.S. Pat. No. 7,003,961 (Kendrick et al.) (Discussed in the Background Art section above). More specifically, the central body and struts displace the flow, creating a region of slow flow downstream of them. The flow in the central flame holding agent capture cavity expands as it burns, as the temperature rises and the density drops significantly. The generated volume partially expands into a lower velocity zone downstream of the strut, as it is a lower resistance path than moving a high velocity flow through the driven cavity in the central body. This flow is moved outward and sheared by the flow passing on both sides of the column. This shear will excite either von Karman vortex shedding or a pair of stable vortices, depending on the design details.

  The axis of rotation of these vortices is parallel to the front of the groove or radial to the centerline of the combustor. A flow feature having these properties is similar to the nozzle tip 24 having a segment having a downstream surface 48 that slopes toward the downstream end of the burner tube 25 with respect to the longitudinal axis B of the burner tube 25. Does not cause flow recirculation over the nozzle / combustor centerline.

  Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

DESCRIPTION OF SYMBOLS 10 ... Combustor 12 ... Premixing (fuel) nozzle 14 ... Combustion casing 16 ... End cover 18 ... Cap 20 ... Reaction zone 21 ... Mixture 22 ... Premixing (fuel) nozzle 23 ... Fuel air premixer 24 ... Segmentation Nozzle tip 24 'Burner tip 24b Nozzle tip 25 Burner tube 25b Burner tube 26 Outer body 27 Inner wall 28 Inner plenum 29 Open inner volume 30 Open end 32 Closed end 33 Upstream end 34 ... Inner surface 35 ... Downstream end 36 ... Outer body outer surface 37 ... Cross section 38 ... Borehole 39 ... Cross section 40 ... Segment 42 ... Inner conduit 44 ... Open proximal end 46 ... Closed distal end 48 ... Segment downstream surface 50 ... Borehole 52 ... Toroidal recirculation area 54 ... Purge groove

Claims (17)

A nozzle tip disposed within the burner tube, wherein the burner tube has an inner wall, an open interior volume having a length extending between an upstream end and a downstream end of the burner tube, a longitudinal axis, and the longitudinal axis. A premixed fuel nozzle for a gas turbine having a cross-sectional area perpendicular to a direction axis, wherein the nozzle tip is
(A) an outer body having an outer body outer surface facing the downstream end of the burner tube, wherein the outer body outer surface has a cross-sectional area smaller than the cross-sectional area of the burner tube;
(B) one or more segments radiating radially outward from the outer body toward the inner wall of the burner tube, each segment being a proximal end disposed adjacent the outer body outer surface; And a distal end disposed in a direction toward the burner tube, wherein each segment is inclined toward the downstream end of the burner tube with respect to the longitudinal axis of the burner tube. Comprising a segment and
When the gas turbine is operating, an axial flow field of a mixture of air and fuel flows around the nozzle tip through the burner tube to provide strong flame holding and flame propagation, and A premixed fuel nozzle for a gas turbine, wherein two or more recirculation zones of different lengths in the direction are created on the nozzle tip by the segments.   The premix fuel nozzle according to claim 1, wherein at least one of the distal ends of the segments extends partially to the inner wall of the burner tube.   The premix fuel nozzle according to claim 1, wherein at least one of the distal ends of the segment extends completely to the inner wall of the burner tube.   The outer body surrounds an inner plenum, the inner plenum adapted to receive cooling air, the outer body has an open end and a closed end, wherein the closed end is adjacent to the inner plenum. The premixed fuel nozzle of claim 1 having an inner surface.   The premix fuel nozzle of claim 4, wherein the closed end has a plurality of cooling holes extending between the inner surface and the outer body outer surface. Each segment is
(A) an inner conduit having an open proximal end and a closed distal end, wherein the open proximal end is in fluid communication with the inner plenum, wherein air passes from the inner plenum to the inner conduit; Internal conduit,
(B) a plurality of segment boreholes between the inner conduit and the segment downstream surface, wherein the boreholes are disposed between the inner conduit and the segment downstream to allow air to pass through each segment from the inner conduit; A segment borehole in fluid communication with the surface,
The premixed fuel nozzle according to claim 4, comprising:   The premix fuel nozzle according to claim 1, wherein the segment downstream surface of each segment is planar.   The premixed fuel nozzle according to claim 1, wherein an angle of the segment downstream surface with respect to a longitudinal axis of the burner tube is in a range of 105 to 165 degrees.   The premix fuel nozzle according to claim 3, wherein the distal end of the at least one segment extending completely to the inner wall of the burner tube is closed and includes a purge groove.   The premixed fuel nozzle of claim 1, wherein each of the segments is circumferentially equally spaced around the outer body.   The premixed fuel nozzle of claim 1, wherein a circumferential cross-sectional area of the proximal end of each segment is greater than a circumferential cross-sectional area of the distal end of each segment.   The premix fuel nozzle according to claim 7, wherein each segment has a U-shaped cross section, the cross section being parallel to the longitudinal axis of the burner tube.   The premix fuel nozzle according to claim 1, wherein each segment has an upstream surface, wherein the upstream surface is smoothly curved toward the segment downstream surface.   The premix fuel nozzle according to claim 1, wherein each segment has an upstream surface, and wherein the upstream surface of each segment is inclined toward a downstream end of the burner tube with respect to a longitudinal axis of the burner tube. A combustor for a gas turbine comprising a reaction zone and one or more premixed fuel nozzles for injecting a mixture of fuel and air into the reaction zone, wherein the at least one premixed fuel nozzle comprises:
(A) a fuel air premixer;
(B) a nozzle tip disposed within a burner tube, wherein the burner tube has an inner wall, an open inner volume having a length extending between an upstream end and a downstream end of the burner tube, and a longitudinal axis. And a cross-sectional area perpendicular to the longitudinal axis, wherein the nozzle tip is
(I) an outer body having an outer body outer surface facing the downstream end of the burner tube, wherein the outer body outer surface has a cross-sectional area smaller than the cross-sectional area of the burner tube;
(Ii) at least one segment radiating radially outward from the outer body toward the inner wall of the burner tube, each segment being a proximal end disposed adjacent the outer body outer surface; And a distal end disposed in a direction toward the burner tube, wherein each segment defines a segment downstream surface inclined toward the downstream end of the burner tube with respect to a longitudinal axis of the burner tube. With segment, with
When the gas turbine is operating, an axial flow field of a mixture of air and fuel flows around the nozzle tip through the burner tube to provide strong flame holding and flame propagation, and A combustor for a gas turbine, wherein two or more recirculation zones of different lengths in the direction are created on the nozzle tip by the segments.   The combustor of claim 15, wherein the at least one or more premixed fuel nozzles is a single central premixed fuel nozzle and the combustor includes at least one different type of outer premixed fuel nozzle.   The combustor of claim 15, wherein the one or more premixed fuel nozzles comprises a single central premixed fuel nozzle and at least one outer premixed fuel nozzle.

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